This invention relates generally to the coding and decoding of motion picture signals and associated audio signals, and more particularly the invention relates to the detection of errors and the propagation of an error indicator in a decoder system for transmitted motion and audio signals.
MPEG is a standard which has been established for the transmission of motion picture signals and associated audio signals. Coding of the signals can be in a program stream or in a transport stream which combines one or more program streams. Video and audio signals are each encoded into separate elementary streams which are packetized to produce PES (packetized elementary stream) packets which are multiplexed in the program and transport stream. Each packet has a header followed by 188 bytes of payload.
The transmitted program and transport streams are received by a system decoder and demultiplexer which separates the audio and video signal packets. These packets are then applied in parallel to respective audio and video decoders as elementary PES packets.
Error conditions in the received transport streams are detected at the front end of the decoder and demultiplexer where packet headers are parsed. However, there is no mechanism for propagating a detected error condition to the decoders of the elementary streams of audio and video packets.